This study is a comprehensive analysis of employer behavior in representation elections supervised by the National Labor Relations Board (NLRB). The data for this study originate from a thorough review of primary NLRB documents for a random sample of 1,004 NLRB certification elections that took place between January 1, 1999 and December 31, 2003 and from an in-depth survey of 562 campaigns conducted with that same sample.